Effect of Al-V-B grain refiner on refining aluminium alloys: Estimation from ab initio calculations

Ab initio calculations based on density functional theory were conducted to estimate the effect of Al-V-B grain refiner on refining aluminium alloys. Al-Ti-B, an industrial grain refiner, was investigated simultaneously to act as a reference. Six interfaces formed by (111) Al with (112) Al3V(Ti), V(Ti)-terminated (0001) V(Ti)B2 and B-terminated (0001) V(Ti)B2 were studied in detail. Interfacial lattice mismatch, work of adhesion and stain-free interfacial energy were calculated for each of these interfaces, respectively. Analysis of interfacial energy demonstrated that Al3V overlayers are less likely to form on the surface of (0001) VB2 surface compared with the Ti-related system. By combination of interfacial lattice mismatch and work of adhesion, it was concluded that VB2 is much more potent in refining aluminium alloys than TiB2, while Al3V is much weaker in nucleant potency compared with Al3Ti.